Nike's Web site shows messages written by a Chalkbot on the Tour de France course.

Not only is Lance Armstrong posting to Twitter from the race, but a Chalkbot -- a robot that writes in water-soluble paint -- is scribing messages onto the road, offering inspiration to the competitors and to cancer survivors.

The Chalkbot takes input from text messages and Twitter posts sent by the public. The robot, a tractor-like device that's pulled around by a truck, then paints those messages in large yellow letters along the Tour de France course.

The letters face the riders so they can read them on their journey during the grueling annual race, which ends July 26 in Paris.

Nathan Martin, CEO of Deeplocal, a mobile software company in Pittsburgh, Pennsylvania, helped design the robot as part of an ad campaign for Nike.

He said the Chalkbot is part of a trend in art and marketing: Digital creations are taking on real-world forms to get noticed and to have greater impact.

"We have so much clutter and no editorship [online]," he said. "You can launch new Web sites all the time, but it's really hard to stand out. I think the way to stand out is for people to think you have a real impact on your lives."

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That sense of true impact is best achieved through real-world manifestations of online art, he said.

The temporary paint messages are a high-tech take on old traditions at the Tour de France, said Derek Kent, a spokesman for Nike.

"If you talk to any cyclist, they'll tell you there's a longstanding tradition to chalk messages of support," he said. "And what we've done is taken that insight and bought it to another level, so that someone in Asia can participate in the Tour and feel a part of something bigger."

The Chalkbot ad campaign ties in with Livestrong, nickname of the Lance Armstrong Foundation, which is devoted to cancer research and was founded by U.S. cyclist Armstrong, a cancer survivor.

Kent said many of the messages drawn by the Chalkbot are from cancer survivors or their friends and family.

A photo of one road message posted on Nike's Web site says "My mom climbed over Mt. Cancer." Another says "If not us who / if not now when."

People who send text messages or Twitter posts will be notified if their notes are chalked onto the road in France, Martin said.

The robot takes a picture of the words on the road and sends that image, along with GPS coordinates, to the person who submitted it, he said.

Martin said the Chalkbot was writing about 200 messages per day in the early days of the tour, which kicked off July 4. Some towns along the route have banned the robot from writing on their streets, but most sections of the course have supported the ad campaign, he said.

The robot writes its messages in paint that washes away quickly, he said.

Martin declined to say how much the robot cost to build but said the effort is far less expensive than developing a television commercial.

The Chalkbot looks somewhat like a farm tractor and is fitted with 48 nozzles that spray out a mixture of air and temporary paint.

A truck pulls the robot along the course at about 5 mph, and a person with a laptop sends commands to the device, telling it which messages to spray onto the road, according to Deeplocal.

To send a message to the Chalkbot, post a message to @chalkbot on Twitter, followed by the tag #LIVESTRONG, or text LIVESTRONG, followed by a message, to 36453.

Messages must be 40 characters or less. Check out this video on Nike's site to see the Chalkbot in action.